Shelf unit



FIG. 1 is a front view of a shelf unit showing my new design.

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 top front perspective view thereof;

FIG. 6 is a left-top front perspective view thereof; and,

FIG. 7 is a top-front perspective view thereof. 

I claim the ornamental design for a shelf unit, as shown and described. 